1. Field of the Invention
This invention relates to a video signal processing apparatus which divides a video signal into multiple video signals and performs magnification processing. The invention is employed in TV walls which display one picture on a big screen composed of plural video monitors.
2. Description of the Prior Art
Video monitors used for a television wall are changing from direct view tube type to projection type. Furthermore, the TV screens are becoming bigger. For a big screen, a video signal processing technique has been developed which divides a video signal into multiple video signals, performs magnification processing, and displays the video signal on a big screen composed of a combination of plural video monitors. As screen size increases, a video signal processing apparatus with a higher quality video signal is required.
FIG. 1 is a block diagram of a video signal processing apparatus in accordance with the prior art. A/D converter 1 converts an analog video signal into a digital video signal. Field memory 2 stores a digital video signal of one field. In an exemplary embodiment of the present invention, a video memory is used which can process a video signal so that an arbitrary domain from an arbitrary position in the field can be magnified with an arbitrary integer magnifying power by programming (e.g. Matsushita Electronic Corp. type MN4711F). Controller 3 may be a microcomputer. The controller 3 programs the field memory 2 and plays a part in magnification processing. Magnification processing means 4 includes memory 2 and controller 3.
FIG. 2(e) is an image of a video signal stored in the field memory 2. A digital video signal of a certain point on the m-th scanning line in the field is defined as Rm and a digital video signal of the point beneath the above mentioned point on the next m1-th scanning line is defined as Rm1. The sizes of these digital video signals which are in a positional relation of on-beneath are shown by a bar graph in FIG. 2(a). In FIG. 1, by programing the field memory 2 with the controller 3 and repeating vertical addressing n times, a video signal in which vertical data is magnified by n-power is obtained. FIGS. 2(b), 2(c) and 2(d) show the cases of 2-power magnification, 3-power magnification, and 4-power magnification, respectively.
In the prior art, however, because only signals with the same data are repetitively displayed, the picture becomes mosaiclike and the picture quality deteriorates.